Fuel for internal combustion engine

ABSTRACT

A fuel for an internal combustion engine is provided which is environment friendly and arranged to minimize corrosion of the internal combustion engine. The fuel is characterized by 50 to 75 percent by weight of an alcohol component including isopropyl alcohol, isobutyl alcohol, and n-butyl alcohol and 25 to 49.9 percent by weight of a hydrocarbon component, wherein the ignition point is not higher than −20° C. Preferably, the alcohol component is 50 to 60 percent by weight while the hydrocarbon component is 40 to 49.9 percent by weight. Also, the alcohol component contains 15 to 30 percent by weight of isopropyl alcohol, 15 to 25 percent by weight of isobutyl alcohol, and 7 to 20 percent by weight of n-butyl alcohol.

FIELD OF THE INVENTION

The present invention relates to a fuel for an internal combustionengine and particularly, to a type of fuel for an internal combustionengine which is environment friendly and can produce a minimum ofpollution.

BACKGROUND OF THE INVENTION

Most common fuel for an internal combustion engine used, for example, inan automobile is gasoline. Gasoline or petroleum fuel when burned in theengine generates unwanted fumes including COx (carbon oxide), NOx(nitrogen oxide), and SOx (sulfur oxide) which are discharged togetheras exhaust gas into the air thus causing air pollution.

For replacement, a variety of alcohol based fuels for internalcombustion engines have been proposed which contain large concentrationsof alcohols. One of those alcohol based fuels is known as disclosed inJapanese Patent Laid-open Publication (Heisei) 9-227880. The knownalcohol based fuel contains 48 to 58 percent by weight of alcohol suchas methyl or isobutyl alcohol. The known alcohol based fuel containing adesired amount of alcohol thus has some advantages. Firstly, the alcoholbased fuel includes a large number of oxygen molecules and when burned,generates less amounts of CO (carbon monoxide) and HC (hydrocarbon)Accordingly, its combusted gas can release a minimum of CO and HC.Secondly, the alcohol based fuel contains a less amount of sulfuringredients and its combusted gas includes a less amount of SOx.Accordingly, the fuel can be environment friendly. Thirdly, the alcoholbased fuel is high in the octane rating and can thus be suited for usein a spark ignition type of the internal combustion engine.

However, the known alcohol based fuel is based on methyl alcohol and maycontain as a greater amount as 40 percent by weight. Commonly as isdesired for reduction of the overall weight, an internal combustionengine used in an automobile is made of aluminum. Aluminum issusceptible to the corrosion by methyl alcohol. It is hence probablethat the internal combustion engine is corroded partially or namely atthe cylinder head with the long-run use of the known fuel containing ahigh concentration of methyl alcohol.

It is thus an object of the present invention to provide a fuel for aninternal combustion engine which is environment friendly and arranged tominimize corrosion of the internal combustion engine.

SUMMARY OF THE INVENTION

A fuel for an internal combustion engine according to the presentinvention is characterized by 50 to 75 percent by weight of an alcoholcomponent including isopropyl alcohol, isobutyl alcohol, and n-butylalcohol and 25 to 49.9 percent by weight of a hydrocarbon component,wherein the ignition point is not higher than −20° C.

The alcohol component at 50 to 75 percent by weight comprises isopropylalcohol, isobutyl alcohol, and n-butyl alcohol. As isopropyl alcohol,isobutyl alcohol, and n-butyl alcohol are greater in the number ofcarbons (C) than methyl alcohol or ethyl alcohol, their corrosive effecton aluminum is lower thus minimizing corrosion of the internalcombustion engine. When the alcohol component is lower than 50 percentby weight, it is overwhelmed by the hydrocarbon component. This willaccelerate the generation of NOx and COx at the combustion thusincreasing NOx and COx in the exhaust gas and polluting the environment.When the alcohol component exceeds 75 percent by weight, it disturbs thegeneration of thermal energy at the combustion hence declining theoutput power of the internal combustion engine and the performance of anautomobile. Since the ignition point of the fuel is not higher than −20°C., the low temperature startup can be ensured at a desired temperature.

Alternatively, the alcohol component including isopropyl alcohol,isobutyl alcohol, and n-butyl alcohol may be 50 to 60 percent by weightwhile the hydrocarbon component is 40 to 49.9 percent by weight. Thehydrocarbon component may comprise aromatic substances including benzeneand xylene and non-aromatic substances.

Preferably, the alcohol component contains 15 to 30 percent by weight ofisopropyl alcohol, 15 to 25 percent by weight of isobutyl alcohol, and 7to 20 percent by weight of n-butyl alcohol.

As its alcohol component contains 15 to 30 percent by weight ofisopropyl alcohol, 15 to 25 percent by weight of isobutyl alcohol, and 7to 20 percent by weight of n-butyl alcohol, the fuel according to thepresent invention can remain stable at the concentration of alcoholsthus ensuring improved characteristics for the driving performance andthe acceleration. Preferably, the weight ratio between isopropylalcohol, isobutyl alcohol, and n-butyl alcohol is expressed by(1.8-2.2):(1.3-1.7):1. This allows the fuel to be favorably used forenergizing an automobile.

The fuel may further contain not higher than 6.0 percent by weight ofMTBE.

As the fuel contains not higher than 6.0 percent by weight of MTBE(methyl tertiary butyl ether), it can produce less amounts of hazardousmatters thus being environment friendly. The smaller the amount of MTBE,the more the fuel will be environment friendly. Preferably, MTBE may be0.3 percent by weight or lower.

The hydrocarbon component in the fuel of the present invention maycontain 0.2 to 1.0 percent by weight of aromatic substances and 48.9 to49.7 percent by weight of non-aromatic substances. With its hydrocarboncomponent doped at the above-mentioned percentage, the fuel can providecharacteristics essential as an automobile fuel even when the amount ofits alcohol component is higher.

BEST MODES FOR EMBODYING THE INVENTION

Embodiments of a fuel for an internal combustion engine according to thepresent invention will be described in more detail.

The fuel for an internal combustion engine contains high concentrationsof an alcohol component and a hydrocarbon component. The alcoholcomponent is a mixture of isopropyl alcohol, isobutyl alcohol, andn-butyl alcohol. As the alcohol component contains isopropyl alcoholwhich is greater in the number of carbon atoms than methyl alcohol, itis less corrosive to aluminum thus contributing to minimum corrosion ofthe internal combustion engine. The alcohol component is included 50 to75 percent by weight in the fuel. When the alcohol component is lowerthan 50 percent by weight, the hydrocarbon component will increase. Thisleads to the generation of NOx and COx during the combustion and causesthe exhaust gas to contain more amounts of NOx and COx. When the alcoholcomponent is higher than 75 percent by weight or oversupplied, it willhardly increase the thermal energy during the combustion but decline theoutput power of the internal combustion engine. In particular, when itsinternal combustion engine burns the fuel, the automobile fails toimprove the running performance or particularly the accelerating rate.It is hence desirable that the fuel contains 50 to 60 percent by weightof the alcohol component.

More specifically, the alcohol component contains 15 to 30 percent byweight of isopropyl alcohol, 15 to 25 percent by weight of isobutylalcohol, and 7 to 20 percent by weight of n-butyl alcohol. As thealcohol component contains 15 to 30 percent by weight of isopropylalcohol, 15 to 25 percent by weight of isobutyl alcohol, and 7 to 20percent by weight of n-butyl alcohol, the fuel allows the alcoholcomponent to be stable and can have the properties essential for anautomobile fuel, and it can remain stable to replace gasoline as thefuel for the internal combustion engine of an automobile withoutimproving the internal combustion engine. It is further desirable thatthe weight ratio between the three alcohols, isopropyl alcohol (X),isobutyl alcohol (Y), and n-butyl alcohol (Z), is expressed byX:Y:Z=(1.8-2.2):(1.3-1.7):1.

The hydrocarbon component of the fuel contains aromatic substances(aromatic compounds) and non-aromatic substances (non-aromaticcompounds). The aromatic compounds include benzene, toluene, xylene, andother aromatic groups having eight carbons and nine or more carbons. Thefuel contains 25 to 49.9 percent by weight of the hydrocarbon component.As the fuel contains such a desired percentage of the hydrocarboncomponent, it can have the properties essential for an automobile fuelwhile including a higher concentration of the alcohol component andfavorably replace the gasoline. Preferably, the fuel contains 40 to 49.9percent by weight of the hydrocarbon component in relation to thealcohol component.

It is desired that the hydrocarbon component contains 0.2 to 1.0 percentby weight of the aromatic substances and 48.9to49.7percent by weight ofthe non-aromatic substances. The hydrocarbon component can thus have theproperties essential for an automobile fuel.

Moreover, the fuel contains not higher than 6.0 percent by weight ofmethyl tertiary butyl ether (MTBE). MTBE functions to increase theoctane rating in the fuel but produces SOx when burned thus beinghostile to the environmental protection. Since MTBE is not higher than6.0percent by weight, it will give less environmental impact whileincreasing the octane rating. The octane rating may further be increasedby modifying the percentage of each ingredient. This allows the amountof MTBE to stay not higher than 0.1 percent by weight and if desired, bedecreased substantially to zero.

The fuel having a higher concentration of the alcohol component is thusas low as −20° C. at the ignition point. As its ignition point is low,the fuel remains ignitable at a low temperature hence contributing tothe low temperature startup of an internal combustion engine. Also, asthe fuel has an octane rating of 94.0 or higher, its performance can beimproved.

The fuel is favorably employed as a fuel for an automobile engine toimprove the characteristics of the engine (including the acceleration,the low temperature startup, and the anti-knocking). The fuel canreplace the gasoline for use in any gasoline-specific internalcombustion engine.

Example 1 of the fuel of the present invention was prepared having theingredients listed in Table 1 and tested for use in an gasoline-specificinternal combustion engine (made of aluminum) for an automobile throughexamining the performance of the automobile and analyzing the exhaustgas. TABLE 1 Alcohol component 56.0 percent by weight Isopropyl alcohol25.0 percent by weight N-butyl alcohol 12.0 percent by weight Isobutylalcohol 18.8 percent by weight MTBE not higher than 0.1 percent byweight Hydrocarbon component   44 percent by weight Aromatic substances 0.8 percent by weight Non-aromatic substances 43.2 percent by weightIgnition point TCC not higher than −20° C. Octane rating 95.9

Also, Example 2 of the fuel of the present invention was prepared havingthe ingredients listed in Table 2 and tested for use in thegasoline-specific internal combustion engine (made of aluminum) for anautomobile through examining the performance of the automobile andmeasuring the exhaust gas. TABLE 2 Alcohol component 56.7 percent byweight Isopropyl alcohol 25.5 percent by weight N-butyl alcohol 12.2percent by weight Isobutyl alcohol 19.0 percent by weight MTBE nothigher than 0.1 percent by weight Hydrocarbon component 43.3 percent byweight Aromatic substances  0.9 percent by weight Non-aromaticsubstances 42.4 percent by weight Ignition point TCC not higher than−20° C. Octane rating 95.6

As the automobile engine consumed Examples 1 and 2 of the fuel, itsperformance was equal to that with gasoline. More particularly, resultsof the low temperature startup and the acceleration were good while noknocking occurred. The exhaust gas was measured where CO (carbonmonoxide) and HC (hydrocarbon) were about 1/10 and 1/4 respectively ascompared with the exhaust gas from the combustion of gasoline. It ishence proved that the fuel is more environment friendly than thegasoline. Also, the test had been repeated throughout the duration ofone year, its results revealed no declination in the performance of theengine but remained at a desired level.

Industrial Applicability

The fuel for an internal combustion engine according to the presentinvention contains carbon-rich alcohols including isopropyl alcohol,isobutyl alcohol, and n-butyl alcohol and can thus be less corrosive toaluminum, minimizing corrosion of the internal combustion engine. As thefuel has 50 to 75 percent by weight of the alcohol component, it canminimize the generation or concentration of NOx and COx in the exhaustgas while ensuring the performance of an automobile engine. Moreover,the ignition point of the fuel is not higher than −20° C., hencecontributing to improvement of the low temperature startup.

1. A fuel for an internal combustion engine characterized by 50 to 75percent by weight of an alcohol component including isopropyl alcohol,isobutyl alcohol, and n-butyl alcohol and 25 to 49.9 percent by weightof a hydrocarbon component, wherein the ignition point is not higherthan −20° C.
 2. A fuel for an internal combustion engine according toclaim 1, wherein the alcohol component is 50 to 60 percent by weight andthe hydrocarbon component is 40 to 49.9 percent by weight.
 3. A fuel foran internal combustion engine according to claim 1 or 2, wherein thealcohol component contains 15 to 30 percent by weight of isopropylalcohol, 15 to 25 percent by weight of isobutyl alcohol, and 7 to 20percent by weight of n-butyl alcohol.
 4. A fuel for an internalcombustion engine according to claim 3, wherein the weight ratio betweenisopropyl alcohol, isobutyl alcohol, and n-butyl alcohol is expressed by(1.8-2.2):(1.3-1.7):1.
 5. A fuel for an internal combustion engineaccording to claim 1 or 2, further containing not higher than 6.0percent by weight of MTBE.
 6. A fuel for an internal combustion engineaccording to claim 1 or 2, wherein the hydrocarbon component contains0.2 to 1.0 percent by weight of aromatic substances and 48.9 to 49.7percent by weight of non-aromatic substances.